Sodium chloride improves photosynthesis and water status in the succulent xerophyte Zygophyllum xanthoxylum
Sodium chloride improves photosynthesis and water status in the succulent xerophyte Zygophyllum xanthoxylum
复制标题
氯化钠改善多汁旱生植物霸王的光合作用和水分状况
DOI：
10.1093/treephys/tpr098
复制
发表时间：
2012-01-01
期刊：
影响因子：
4
通讯作者：
Wang, Suo-Min
中科院分区：
文献类型：
--
作者：
Ma, Qing;Yue, Li-Jun;Wang, Suo-Min
花椒是一种C-3级木本植物，是一种适应干旱环境的肉质旱生植物。我们前期的研究表明，干旱条件下Na+对花椒的生长有积极的促进作用，这与叶片中Na+的高积累密切相关。为了揭示Na+积累提高花椒抗旱性的生理机制，在砂培试验中对3周龄的花椒幼苗进行了一系列外源盐浓度(5~150 mM)的处理。在盆栽试验中，幼苗在有或没有额外的氯化钠(50 Mm)的情况下也受到水分亏缺(田间持水量的30%)的影响。结果表明，50 mM的盐胁迫可显著提高花椒叶片的相对含水量，降低叶片水势，提高叶片膨压和叶绿素浓度，从而提高植物的整体光合作用活性(即光合速率和水分利用效率)，从而缓解水分亏缺对花椒生长的不利影响。此外，50 mM的氯化钠可以缓解水分亏缺对花椒光系统II活性的抑制作用。Na+对总渗透势的贡献从对照的8%下降到水分亏缺的植株的13%，而在50 mM盐胁迫下的植株则下降到28%，而K+的贡献则从13%显著下降到8%。这些结果表明，在干旱环境下，花椒能够在叶片中积累较高浓度的Na+，并直接用于渗透调节，同时叶片的水合作用和光合作用活性也得到改善。
Zygophyllum xanthoxylum, a C-3 woody species, is a succulent xerophyte that is well adapted to arid environments. Our previous investigations showed that Na+ has a positive effect on the growth of Z. xanthoxylum under drought conditions, which was closely related to high Na+ accumulation in leaves. To reveal the physiological mechanisms underlying how Na+ accumulation improves the drought resistance of Z. xanthoxylum, 3-week-old seedlings were treated with a series of additional external NaCl concentrations (5-150 mM) in sand culture experiments. Seedlings were also subjected to water deficit (30% of field water capacity) in the presence or absence of additional NaCl (50 mM) in pot experiments. The results indicated that 50 mM NaCl could mitigate deleterious impacts of water deficit on the growth of Z. xanthoxylum, by improving the relative water content, inducing a significant drop in leaf water potential and, concomitantly, increasing leaf turgor pressure and chlorophyll concentrations resulting in an enhancement of overall plant photosynthetic activity (i.e., photosynthetic rate and water use efficiency). Furthermore, NaCl (50 mM) could alleviate the inhibitory effect of water deficit on the activity of photosystem II in Z. xanthoxylum. The contribution of Na+ to the total osmotic potential varied from 8% in the control to 13% in plants subjected to water deficit and, surprisingly, to 28% in plants grown in the presence of 50 mM NaCl under water deficit; however, the contribution of K+ significantly decreased from 13 to 8%. These findings suggest that, under arid environments, Z. xanthoxylum is able to accumulate a high concentration of Na+ in its leaves and use it directly for osmotic adjustment, which was coupled with an improvement in leaf hydration and photosynthetic activity.